The use of towed trailers behind automobiles and lightweight trucks has become quite commonplace and the hazards associated with such vehicular combinations are well known. A particularly dangerous characteristic of the towed trailer is its tendency to sway from side to side under conditions initiated by sudden turns, cross winds, air drafts produced by passing trucks, improper loading of the trailers, among other things. Certain combinations of various parameters such as the length of the trailer tongue, the weight of the load, and the surface of the highway increase the tendency for the trailer to sway and even increase the intensity or amplitude of the swaying action once it has started. Under such conditions it is difficult if not impossible for the driver of the towing vehicle to maintain control of his vehicle. The combination of the towing vehicle and the trailer in the presence of such critically related parameters contributes an unstable mechanical system.
Prior art disclosures have been limited in scope and have provided for devices only to lessen or prevent the swaying motion of trailers. Some of these devices are complicated in structure involving pulleys or spools, brake shoes, telescoping structures employing friction or hydraulic damping means and usually have numerous parts requiring periodic replacement otherwise the devices may become dangerous within themselves. Furthermore, some prior art devices employ only one means of connection on only one side of the longitudinal axis of the towed trailer to obtain sway control presenting a potentially dangerous condition should the trailer tongue break away from the towing vehicle when in motion. Nearly all of the prior art structures require component parts that are difficult to install an require complicated instructions for mounting and operation.